Full Breakdown
Jellyfish Prompt Partial Shutdown at France’s Gravelines Nuclear Plant
8/28/2026, 8:51:04 AM
Event Overview
A sudden influx of jellyfish in the seawater used for cooling forced Électricité de France (EDF) to shut down three of the six reactors at Gravelines nuclear power station in northern France. Units three, four and six were taken offline, while units one and two continue operating at reduced power as a precaution. A third unit has been shut down since 10 August and a fourth remains closed for inspection. Unit three was briefly re-connected to the grid on 18 August after an earlier wave of jellyfish earlier in the month.
Background
Gravelines, located between Dunkirk and Calais in the Hauts-de-France region, draws cooling water from a canal linked to the North Sea. Warmer sea temperatures raise plankton levels, attracting several native jellyfish species that can clog filtration systems. EDF noted that the plant experienced a similar jellyfish-related shutdown last August. Comparable incidents have been recorded at Scotland’s Torness plant in 2011 and Sweden’s Oskarshamn plant in 2013, though such events are rare.
Operational Impact
Each of Gravelines’ six reactors generates 900 megawatts of electricity, meaning the shutdown of three units reduces the station’s output by roughly 2.7 gigawatts. The reduced-power operation of units one and two further limits total generation. EDF has partnered with local fishermen, who capture jellyfish offshore and release them farther out to sea, in an effort to keep filtration systems clear.
Official Response
EDF reported that the jellyfish blockage affected the seawater filtration system used for reactor cooling, prompting the shutdowns as a safety measure. The company emphasized that the remaining reactors are being monitored closely and that the plant’s safety protocols remain fully operational.
Outlook
While the current shutdowns are temporary, EDF’s collaboration with fishermen aims to mitigate future jellyfish intrusions during warm months. The incident highlights the vulnerability of coastal nuclear facilities to ecological changes linked to rising sea temperatures.
